1. Field of the Invention
The present invention relates to a vehicle illumination system. In particular, the invention relates to a vehicle illumination system that provides illumination not only for the vehicle but also for other vehicle systems such as a range finding system or a data transfer system.
2. Related Art
In modern vehicles, systems are often provided that assist the driver. An example of such a system is an adaptive cruise control that detects the distance of the vehicle to a vehicle driving in front. If the distance to the vehicle in front decreases, the driver assistance system automatically slows down the vehicle. Such a system needs to accurately determine the distance to the vehicle in front. For a distance determination, three-dimensional (3D) cameras working with the time-of-flight principle may be used. A range finding device using a modulated light source is known from EP 1 159 636 B1, in which a one- or two-dimensional array of light sources and corresponding detectors are used. The German patent application DE 101 38 531 A1 describes a 3D range finding device that employs pulsed illumination and a CMOS-sensor for time-of-flight determination. Furthermore, photonic mixer devices (PMD) are known for recording images with range information, e.g., the PMD [Vision] A2 3D video range camera of PMD Technologies, which uses light emitting diodes at 870 nm with a frequency modulation of 1 to 16 MHz. Furthermore, a solid state time-of-flight range camera is produced by the Swiss Center for Electronics and Microtechnology Inc. (CSEM), e.g., the Swiss Ranger SR-3000, which uses infrared light modulated at 20 MHz for illumination. These and similar systems can be integrated in vehicles to determine the distance to obstacles or other vehicles. These distance measurement systems rely on modulated light that is emitted by a light source and reflected by the obstacle. In vehicles with conventional illumination systems, additional illumination systems have to be integrated for providing the high frequency modulated light, which is necessary for range finding. The integration of such an additional illumination system is often very difficult as suitable space is often not available. If such a system is for example integrated behind the radiator grille, it is necessary to provide a multitude of different illumination systems as the radiator grilles of different vehicle manufacturers often differ substantially. Accordingly, it is very costly to provide a vehicle with a range finding device comprising an additional illumination system.
Furthermore, for driver assistance systems, it is desirable to exchange information between vehicles. At present, there is no system that can be easily integrated in a vehicle without high costs and that enables an exchange of information between vehicles. European patent application EP 1 786 174 A1 discloses a data transfer system that transfers data such as music, videos or games between vehicles using a wireless local area network. In such a system, transmitters and receivers as well as processors have to be provided, and establishing a local area connection between vehicles may not always be possible due to security restrictions that are in place to prevent misuse of such a system. Data transfer systems are known that use modulated infrared light to transfer the data. Such systems include, e.g., remote controls transferring information to a receiver or mobile telephones and which may communicate to each other through an infrared port. These systems generally use special units for emitting modulated infrared light. Vehicles may be equipped with an optical remote control system for opening the doors of the vehicle, but these systems generally comprise infrared light emitting diodes in a mobile sending unit and receptors on the vehicle. These systems are at present not suitable to exchange information between vehicles. Furthermore, additional infrared sending units would have to be integrated in the vehicle, which again would require space and additional costs.
Accordingly, there is a need to provide a compact, multifunctional and cost efficient illumination system in a vehicle. Particularly, there is a need to provide an illumination system that provides an illumination of the vehicle as well as an illumination for a range finding system and/or a data transfer system.